Suspension Devices for Vibration Testing of Structures

Space structures in general experience free-free vibrational boundary conditions that are not readily replicable on the ground. To conduct vibration tests of such structures on Earth, special devices must be used to support the weight of the structures without introducing any constraining forces that impose boundary conditions that detract from the simulation of the desired free-free boundary conditions in outer space. Previous supports all have certain disadvantages. For example, long cables entail very tall ceilings and generate undesirable pendulum effects, the masses of air pads incorporated into a suspended structure can distort the dynamical characteristics of the structure, pneumatic/electric devices are usually highly complex, and springs are limited by small domains of operation (strokes). To overcome these difficulties, a simple and inexpensive support was designed that includes a noncircular cam, a torsion spring, and a cable.